11:16 <LW> hello

11:25 <LW> Does systemtap require kernel version? my stap version is 2.9/0.165, can i use the linux kernel 4.19?

14:27 <fche> hi LW

14:28 <LW> yes

14:28 <fche> since the kernel does not maintain a stable api/abi, systemtap needs to play catch-up with kernel changes

14:29 <fche> stap 2.9 is from 2015-10-08; it cannot be compatible with a much younger kernel, though some distros backport some compatibility fixes

14:29 <fche> a new systemtap works with very old kernels as well as current ones

14:30 <LW> if i want use 4.19 kernel, i must use a new stap, such as stap 4.1?

14:31 <fche> probably, yes

14:32 <LW> ok, i will have a try, thanks

14:32 <fche> righto

14:32 <fche> what distro are you running?

14:34 <LW> i am using ubuntu 16.04, but i build the my own kernel from kernel source code, and i install the stap with the command: apt install systemtap.

14:35 <fche> aha. if you are able to build your own kernel, you'll find it straightforward to build a newer stap

14:35 <fche> we're thinking about setting up ubuntu PPAs with newer systemtap builds for people like you, but don't have it yet

14:39 <LW> I'm a newbie for systemtap. I encountered an error during build from src, so i give up

14:43 <fche> what was the error?

14:45 <LW> i'll try again later and email the results

15:03 <LW> if i build my own kernel, i must

15:04 <LW> if i build my own kernel, i must use the not-striped kernel and ko?

15:05 <fche> for some stap scripts, you'll want to keep the unstripped CONFIG_DEBUG_INFO=y kernel around on disk

15:08 <LW> i have config the CONFIG_DEBUG_INFO=y in kernelsrc/.config, but i use this command to install ko: make INSTALL_MOD_STRIP=1 modules_install, Should I not specify the INSTALL_MOD_STRIP=1 , i should use make INSTALL_MOD_STRIP=0 modules_install

15:09 <LW> ?

15:09 <fche> if you want to probe the modules, you'll want to keep an unstripped copy around

15:10 <fche> stap can run based on a build tree that matches a running kernel

15:10 <fche> it does not have to read content only from the installed /lib/modules/.... directory

15:10 <fche> so you can make install any way you want

15:10 <fche> and then run stap -r /path/to/original/build/tree that contains the full vmlinux and .ko's

21:34 <agentzh> fche: i've noted that the std tapset func proc_mem_rss() returns very diferent values than the RSS value reported by tools like top.

21:35 <agentzh> the former is MM_FILEPAGES + MM_ANONPAGES while the latter seems to have

21:35 <agentzh> MM_SHMEMPAGES added as well.

21:36 <agentzh> should we adjust proc_mem_rss() accordingly?

21:43 <agentzh> according to /proc/PID/status, VmRSS = RssAnon + RssFile + RssShmem, it appears.

22:02 <agentzh> fche: how does this patch look? https://gist.github.com/agentzh/08df635987f70a8eca21df360a46ad84

22:03 <agentzh> it makes the return value exactly the same as RSS reported by /proc/xxx/status and top.

23:27 <fche> agentzh, looks good to me, except perhaps for compatibility purposes may want to put that shmempages addition as a %( systemtap_v >= "4.2" ? .... %) kind of thing

23:27 <fche> so that existing users are not affected

23:27 <fche> I guess > "4.2"

23:53 <agentzh> fche: okay. and also a note to NEWS?

23:53 <fche> sure

23:53 <fche> thanks dude

23:53 <agentzh> k

23:53 <agentzh> sure